Many attempts have been made to treat limestone fines resulting from the processing of limestone for the purpose of reducing dust and pollution problems or for utilizing the fines at the processing plant for making other products. These attempts to agglomerate fines have been only moderately successful since the chemical nature of limestone is such that it is not readily soluble in water or in other desirable chemicals which would allow the necessary physical changes for agglomeration to take place. In some cases compression of the fines has been used to form agglomerals. Attempts have also been made to incorporate the limestone fines with materials that are soluble and which carry the limestone fines to form granules that can be easily and readily handled. See, for example, Yee, et. al., U.S. Pat. No. 2,307,253. In further instances small amounts of a binder material have been used to assist in the agglomeration of the limestone fines. See, for example, Perrine U.S. Pat. No. 4,015,973.
In processes using extrusion, cutting of the extrudite has proven to be a major problem. Mechanical cutters cause the formation of non-uniform agglomerations of smaller sections and show a tendency to form "balls" by squeezing the moisture content to the surface. Air cutting creates granules of non uniform moisture content and results in environmental problems related thereto.
All of these processes have generally resulted in products which are friable and subject to disintegration upon handling. The process of this invention offers a solution to most of the problems previously encountered and provides for the successful pelletizing of limestone fines into granules of specified size, hardness, and dispersion characteristics.